Fabricating semiconductor devices typically includes processing a substrate such as a semiconductor wafer using a number of semiconductor fabrication processes. For example, lithography is a semiconductor fabrication process that involves transferring a pattern from a reticle to a resist arranged on a semiconductor wafer. Additional examples of semiconductor fabrication processes include, but are not limited to, chemical-mechanical polishing (CMP), etching, deposition, and ion implantation. Multiple semiconductor devices may be fabricated in an arrangement on a single semiconductor wafer and then separated into individual semiconductor devices.
Metrology processes are used at various steps during a semiconductor manufacturing process to monitor and control one or more semiconductor layer processes. Some of these characteristics include the flatness and thickness uniformity of the wafers. While conventional metrology systems may be able to monitor and control these characteristics, they are generally utilized for handling unpatterned/bare wafers. Therein lies a need for systems and methods for wafer geometry measurements suitable for any wafers, including patterned wafers, without the aforementioned shortcomings.